PDF Math 8: Integers - UC Santa Barbara Math 8: Integers Spring 2011; Helena McGahagan 1. Let a,b ∈ Z. Write the definition of the highest common factor of a and b. Then, negate this definition. 2. (a) Let a,b,d ∈ Z. Consider the equation as+bt = d. We want to find integer solutions to this equation (i.e., find s,t ∈ Z).